1. Field of the Invention
The present invention relates to a portable cellular phone and an external adapter which is used for a portable cellular phone.
2. Description of the Background Art
In a conventional portable cellular phone 601, as shown in FIG. 6, a transmit signal is radiated from a portable cellular phone transmitting antenna 604 through a portable cellular phone transmit amplifier 602 and a portable cellular phone transmit filter 603, and a receive signal is received at a portable cellular phone receiving antenna 605 and thereafter supplied to a portable cellular phone receive amplifier 607 through a portable cellular phone receive filter 606. A transmit switch 608 is disposed between the portable cellular phone transmit filter 603 and the portable cellular phone transmitting antenna 604, and is connected to an external transmitting antenna 609 as well. Further, a receive switch 610 is disposed between the portable cellular phone receiving antenna 605 and the portable cellular phone receive filter 606, and is connected to an external receiving antenna 611 as well.
Japanese Patent Application Laid-Open Gazette No. 5-347584 discloses a conventional portable cellular phone and an external adapter for a portable cellular phone. As shown in FIG. 7, a transmit signal which is modulated by a modulation part 702 in a portable cellular phone 701 is switched to an intermediate frequency signal line 704 by an intermediate frequency switch relay 703 and transmitted to an on-vehicle booster 706 through a coaxial cable 705, and the intermediate frequency transmit signal which is transmitted to the on-vehicle booster 706 is converted into a transmit frequency by a voltage control oscillator (VCO) 707 and a transmit mixer 708. A receive signal which is received by the on-vehicle booster 706 is converted into an intermediate frequency by the voltage control oscillator (VCO) 707 and a receive mixer 709, transmitted through the coaxial cable 705 and the intermediate frequency signal line 704, and switched to a demodulation part 710 by the intermediate frequency switch relay 703.
In the conventional portable cellular phone 601, where the external transmitting antenna 609 and the external receiving antenna 611 are used, a signal is transmitted and received through the transmit switch 608, which is disposed between the portable cellular phone transmitting antenna 604 and the portable cellular phone transmit filter 603, and the receive switch 610 which is disposed between the portable cellular phone receiving antenna 605 and the portable cellular phone receive filter 606.
However, since the transmit switch 608 is disposed after the portable cellular phone transmit amplifier 602 which uses a loss which is created at the transmit switch 608, an output power of the portable cellular phone transmit amplifier 602 must be high. Further, since the receive switch 610 is disposed before the portable cellular phone receive amplifier 607, a Noise Figure (NF) of a receiving system deteriorates. In a satellite communication system or the like which demands transmitting with a high output power and receiving with a high sensitivity, in particular, where the external transmitting antenna 609 and the external receiving antenna 611 are to be used, a high output power of the portable cellular phone transmit amplifier 602 and a low NF of a receiving system are a problem to be solved.
In addition, in the conventional portable cellular phone and an external adapter for the same, as shown in FIG. 7, the transmit signal is transmitted in the intermediate frequency band from the portable cellular phone 701 to the on-vehicle booster 706.
However, it is necessary to convert the transmit signal of the intermediate frequency band into the transmit frequency by the voltage control oscillator (VCO) 707 and the transmit mixer 708 which are disposed in the on-vehicle booster 706, which inconveniently increases the size of the on-vehicle booster.
The present invention, to solve the current problem as described above, aims at providing a portable cellular phone and an external adapter for the same, with which it is possible to suppress an increase in an output power of a portable cellular phone transmit amplifier due to a loss at a transmit switch associated with use of an external transmitting antenna, to reduce a deterioration of an NF of a receiving system due to a loss at a receive switch associated with use of an external receiving antenna, and to minimize an increase in the size of an external adapter.
A portable cellular phone according to a first aspect of the present invention comprises: a transmitting portion which includes a portable cellular phone transmit amplifier which amplifies a transmit signal and a transmit switch part which is disposed on the input side to the portable cellular phone transmit amplifier so as to switch whether to output the transmit signal to an external adapter or to the portable cellular phone transmit amplifier; and a receiving portion which includes a portable cellular phone receive amplifier which amplifies a receive signal and a receive switch part which is disposed on the output side to the portable cellular phone receive amplifier so as to switch between the receive signal which is amplified and the receive signal which is supplied from an external adapter.
A second aspect of the present invention is directed to a portable cellular phone external adapter which comprises: a transmit amplifier part which includes a transmit amplifier and a transmit filter, the transmit amplifier amplifying the transmit signal which is outputted to outside from the transmit switch part of the portable cellular phone, the transmit filter passing the transmit signal which is amplified; an external transmitting antenna for transmitting a signal which is outputted from the transmit amplifier part; an external receiving antenna; and a receive amplifier part which includes a receive amplifier and a receive filter, the receive amplifier amplifying the receive signal which is received by the external receiving antenna, the receive filter passing the receive signal which is amplified and supplying the receive signal to the receive switch part of the portable cellular phone.
A third aspect of the present invention is directed to a portable cellular phone apparatus which comprises: a portable cellular phone; and a portable cellular phone external adapter, wherein the transmit switch part of the portable cellular phone is connected to an input of the transmit amplifier of the portable cellular phone external adapter, and the receive switch part of the portable cellular phone is connected to an output of the receive amplifier of the portable cellular phone external adapter.
A further aspect of the present invention is directed to a portable cellular phone external adapter which comprises: a transmit amplifier part which amplifies the transmit signal which is outputted to outside from the transmit switch part of the portable cellular phone; a receive amplifier part which includes a receive amplifier and a duplexer, the receive amplifier amplifying the receive signal and outputting the amplified signal to the receive switch part of the portable cellular phone, the duplexer being connected with the output from the transmit amplifier part and an input to the receive amplifier; and an external transmitting/receiving antenna which is connected to the duplexer.
Another aspect of the present invention is directed to a portable cellular phone apparatus which comprises: a portable cellular phone; a transmit amplifier part which amplifies the transmit signal which is outputted to an external adapter from the transmit switch part of the portable cellular phone; a receive amplifier part which includes a receive amplifier and a duplexer, the receive amplifier amplifying the receive signal and outputting the amplified signal to the receive switch part of the portable cellular phone, the duplexer being connected with the output from the transmit amplifier part and an input to the receive amplifier; and an external transmitting/receiving antenna which is connected to the duplexer.
According to a still further aspect of the present invention, the transmit amplifier part is preferably disposed indoors, an output from the transmit amplifier part is connected via a cable to the duplexer of the receive amplifier part which is disposed in the vicinity of the external transmitting/receiving antenna which is disposed out of doors, and an output from the receive amplifier of the receive amplifier part is preferably connected via a cable to the receive switch part of the portable cellular phone.
According to further aspect of the present invention, in the portable cellular phone apparatus, the portable cellular phone preferably comprises an external adapter detector part which detects connection to the portable cellular phone external adapter, the transmit amplifier part and/or the receive amplifier part operates preferably in response to an external power source which is disposed separately from the portable cellular phone, and supply of power to the portable cellular phone transmit amplifier and the portable cellular phone receive amplifier is preferably stopped when the external adapter detector part detects connection to the portable cellular phone external adapter.
According to a further aspect of the present invention, in the portable cellular phone apparatus, supply of power to the receive amplifier part may be realized using a cable for receive signal.
According to another aspect of the present invention, in the portable cellular phone apparatus, the external power source preferably has a function of operating the portable cellular phone and charging up an internal power source which is disposed inside the portable cellular phone.